Power steering oil overheating?

Can't help. Never heard of this problem. Wow! This would pizz me off to no end!

 

Have you always run oil in the PS? I know if you switch from hydraulic fluid to oil and don't purge all the hydraulic oil out of the system you could possibly have foaming problems, which maybe could cause overheating. Does the fluid look foamy after you been driving for a ways?
Is the power steering noisy? maybe some air trapped somewhere? Changing the filter sounds like a good idea to me.
Maybe the old PS pump left some crap in the lines?

 

Have you replaced the filter? A clogged filter will cause overheating.

 

Power steering, like any hydraulic device, it's imperative that the system be completely flushed clean. Sounds like there's still metal in the system. I was told engine oil was fine, but that was years ago. And hydraulics do run warm.
Interesting power steering story, I had a '82 Western Star conv. with PS, and one day driving down the road, I hear this, POW, and nothing else. So naturally, I pulled over, opened the hood, oil EVERYWHERE, and the dipstick on the reservoir was gone. So I called a shop I trusted, the SM asked, "What color was the oil"? I said, "pretty dark", he said, "the seal on the PS pump went out, and oil from the motor was being forced into the PS reservoir, and it filled it up and blew the dipstick out". A new pump, and I was on my way.

 

Is it the small plastic reservoir? Severe duty with assist ram on the right side? PS cooler?
We had a truck doing the same and ended up putting a larger reservoir on it, more volume =lower temps.
Also I think you should be running automatic trans fluid in it, not engine oil.

 

In heavy applications 15/40 works the very best, we found that out in the twin steer cement trucks. also a common problem with a system overheating is the driver continually moving the wheel, we had one unit continually had seal and pump problems I went for a drive with him and he continually was moving the wheel back and forth, I asked him why he felt he had to do that he said it gave him something to do, I told him he was driving like an Englishman and try to keep the wheel as stable as possible.
We had heavy duty application that we had to install the larger tank and move the tank down to get a cooler air flow.

 

You can buy one of those meat thermometers and stick it into the p/s reservour and see what temps it is actually building to. Excessive temps are being caused from restriction and/or constant use. If you have seized or very stiff steering components, like kingpins, the steering will over heat. Jack up the front end and move the wheels side to side by hand.

 

I didn't have to worry about any of that with the ol' Pete (below) It had manual steering.

 

the filter is inside the reservoir on a kw its a nelson filter 57904 and on the reservoir it states to use dexron mercon atf only